题目

Can you guess if they ________ to play basketball with us ? I think they’ll come if they _______ free . A. come, are    B. will come , will be    C. will come , are    D. come , will be   答案：C已知黑尿症是常染色体单基因隐性遗传，两个都是黑尿症基因携带者的男女结婚，预测他们的孩子患黑尿症的概率是 [　　] A．100％B．75％C．50％D．25％